Skull. Sphenoid and ethmoid bones
János Hanics MD SKELETAL SYSTEM MAIN PARTS OF THE SKULL
•Constitute by 22 bones: •neurocranium (8) – UNPAIRED: frontal, occipital, sphenoid, ethmoid bones PAIRED: temporal, parietal bones •viscerocranium (14) -UNPAIRED: mandibule, vomer. PAIRED: nasal, maxilla, zygomatic, lacrimal, palatine, inferior nasal concha
Their role – formation of cavities, protect viscera, voice formation, initial portions of the gastrointerstinal and respiratory systems, insertion of muscles (mascication, head movements)
Cavities: Cranial cavity, Nasal cavity, Paranasal sinuses Oral cavity, Orbit, (Tympanic cavity, Inner ear) Joints between the cranial bones
• Synchondrosis, synostosis (cartilagineal and bony connections)
• Sutures – Coronal – Sagittal – Lambdoid CALVARIA AND BASE OF THE SKULL
Calvaria
External aspect of calvaria Base of the skull
Internal aspect of calvaria BASE OF THE SKULL (INTERNAL AND EXTERNAL ASPECT) FOSSAE CRANII
Anterior cranial fossa
MIddle cranial fossa
Posterior cranial fossa
• Posterior cranial fossa: • Anterior cranial fossa: • Occipital, temporal bones, frontal, ethmoid, lesser parietal bones wings of sphenoid • Middle cranial fossa: sphenoid, temporal bones, parietal bones BONES OF NEUROCRANIUM
Parietal bone Frontal bone Temporal bone
Ethmoid Sphenoid BONES OF THE SKULL
SPHENOID ETHMOID SPHENOID – Form the external and internal aspect of the base of the skull – Connected to frontal, ethmoid, temporal, zygomatic, parietal, maxilla, palatine, vomer and occipital bones – Bordering the neurocranium and viscerocranium – Constitute the wall of temporal, infratemporal and pterygopalatine fossae Parts of sphenoid:
- Body - Greater wing - Lesser wing - Pterygoid process POSTERIOR ASPECT
SUPERIOR ASPECT Body of the spenoid – sphenoidal sinus
ANTERIOR ASPECT
Aperture of the spenoidal sinus Opens to the nasal cavity Sphenoid Body of sphenoid: - (cuboid shape)
- Posterior surface - connected to the basilary part of the occipital bone
- Inferior surface - connected to vomer
- Superior surface - sella turcica, tuberculum sellae, dorsum sellae, (anterior/middle/posterior clinoid process)
- Anterior surface – looking to the nasal Occipital bone cavity (aperture of sphenoidal sinus)
- Lateral surfaces – origin of greater wings and the position of carotic grooves Sphenoid
Surfaces of the greater wing: - orbital surface
- maxillar surface (around foramen rotundum)
- temporal surface
- infratemporal surface
- cerebral surface
PTERYGOID PROCESS
PARTS: -lateral and medial lamina - scaphoid fossa - pterygoid fossa
corpus SPHENOID - OPENINGS
- superior orbital fissure - optic canal - foramen ovale - foramen rontundum - foramen spinosum - pterygoid canal ASPECTS OF SPHENOID
ANTERIOR ASPECT POSTERIOR ASPECT
INFERIOR ASPECT SUPERIOR ASPECT ETHMOID SUPERIOR ASPECT ANTERIOR ASPECT
LATERAL ASPECT ETHMOID
- irregular bone - Form the wall of orbit and nasal cavity – Connects to frontal, sphenoid, lacrimal and maxilla – The lateral massive parts contain the - labyrinth - inside cavtities (ethmoidal cells) – It forms with vomer the bony nasal septum ETHMOID Parts:
- cribriform plate and foramina
- perpendicular plate
- orbital plate
- ethmoidal labyrinth (cellulae)
- crista galli ETHMOID
Cribriform plate, crista galli,
Ethmoid cells, orbital plate ETHMOID Perpendicular plate and crista galli ETHMOID
•Superior and middle nasal concha ETHMOID
Figure 7.7 ETHMOID
Ethmoidal bulla
Semilunar hiatus Uncinate process superior lateral Ethmoid - orbital plate CAVITIES BORDERED BY THE ETHMOID
ANTERIOR CRANIAL ORBIT FOSSA Lamina papyracea
Lamina papyracea (REMOVED) NASAL CAVITY Recommended note